The compound phenylthiobutyl-isoquinoline of the formula ##STR2##
and its preparation starting from L-serine is described, e.g., in U.S. Pat. No. 5,484,926, incorporated herein by reference. This compound is a valuable intermediate for the manufacture of pharmacologically active compounds, suitable for the treatment of viral infections, especially those caused by HIV and other retroviruses, described in U.S. Pat. No. 5,484,926, e.g., at columns 16 and 17, such as represented by formula ##STR3##
wherein Ph is phenyl PA1 (a) reacting diprotected L-serine of formula ##STR5## PA1 (b) reacting the resulting phenylthio compound of formula ##STR6## PA1 (c) reducing a resulting halogen ketone of formula ##STR7## PA1 to the corresponding halogen alcohol of formula ##STR8## PA1 (d) treating the halogen alcohol of formula V with abase to form the [(R)-1-[(S)-oxiran-2-yl]-2-phenylthio-ethyl]carbamic acid ester of formula ##STR9## PA1 (e) reacting the carbamic acid ester of formula IV with N-tert.-butyl-decahydro-(4aS, 8aS)-isoquinoline-3(S)-carboxarnide of formula ##STR10## PA1 (f) treating the resulting compound of formula ##STR11## PA1 (a) silylating a carbamate group of a compound of formula VII in the presence of a lower-alkyl-lithium to form a silyl-protected compound; and PA1 (b) alkylating the silyl-protected compound in the presence of dihalogenated methane with a lower-alkyl-lithium to produce a halogen ketone of formula VI. PA1 methyl (1R, 2R)-[1-phenylthiomethyl-3-[(3S, 4aS, 8aS)-3-tert. -butoxycarbamoyl-decahydroisoquinol-2-yl]-2-hydroxypropyl]-carbamate; PA1 methyl [(R)-1-[(S)-oxiran-2-yl]-2-phenylthio-ethyl]-carbamate; PA1 methyl (1R, 2S)-[3-chloro-2-hydroxy-1-(phenylthiomethyl)-propyl]-carbarnate; PA1 methyl [3-chloro-2-oxo-(R)-1-(phenylthiomethyl)-propyl]-carbamate and PA1 methyl (3-phenylthio-(R)-2-methoxycarbonylamino)-propionate.
and pharmaceutically acceptable salts thereof.